1. Field
The following description relates to an apparatus to control a position of a camera module.
2. Description of Related Art
In order to provide portable communication terminals, such as mobile phones, personal digital assistants (PDAs), portable personal computers (PCs), and other similar electronic devices, it is desired for a camera module for such portable communication terminals to have a small thickness, with a structural configuration that is able capture a high resolution image. In order to satisfy such configuration, a lens is needed to be included in the camera module with a high aspect ratio, capable of performing effective autofocusing, optical image stabilization (OIS), or the like. However, in order to perform autofocusing or OIS, it is necessary to accurately detect a current position value of the lenses and determine an accurate position of the lenses.
As an existing technology, a method to perform position control using a hall sensor and a magnet for sensing a position may be used.
In the case of using the hall sensor, a separate magnet may be required. In this case, a reference value for a position of the hall sensor may be changed, depending on temperature or other external particulars. Therefore, in order to correct such a problem, an additional circuit such as a low pass filter, an automatic gain control (AGC), a differential to single amplifier, an analog to digital converter, or the like, is required.
Further, when implementing an external hall sensor in the camera module, a bias current (having a level of several milliamperes for example) to drive the hall sensor may be consumed, and current may be additionally consumed by various amplifiers (AMPs), and other electronic circuits.
In order to solve problems such as mechanical design limitations of camera modules, additional current consumption, and a rise in material costs, and other problems, as described above, an apparatus configured to perform position detection and position control without using the hall sensor is required.